Carol Davis's daughter died of heart failure in August following a period of illness. Three months later she remains unburied because Carol lacks the funds for a funeral.

Now 59, Carol spent two years living on the streets after serving a prison sentence. Her drug habit began 16 years previously and she faced a brief and painful future. Then she was referred to St Mungo's, a charity set up 43 years ago to provide shelter and support for the homeless.

She was given a bed in a hostel and, most crucially, practical and psychological support. A month ago the charity found her a flat and is granting her £800 towards the cost of burying her daughter.

"Without them I would be back on the street," she says. "Other hostels gave me a bed but no help. Here I've had the same key worker all the way through. She rings me three times a week to see if I'm OK and I can call her day or night. When I came here I was too scared to go out on my own but she would come with me to appointments and she's given me my confidence back."

St Mungo's, which began as a single volunteer-staffed hostel in London, now operates more than 100 accommodation and support centres around the capital and the south of England. It has pioneered specialist hostels for the elderly, the mentally ill, rough sleepers with alcohol dependency, and asylum seekers, and it aims to resettle them back into society through job training and life skills programmes. Its job training programme is the largest of its kind for homeless people in the country. Guests are assigned a volunteer mentor who steers them through the bureaucratic and mental challenges of resuming independent living, and helps them find training, jobs and settled accommodation.

"We're always there in the background in case social workers aren't doing what they should," says Nicola Hilliard, 39, who has been a volunteer mentor for three months and has herself experienced homelessness.

"If there is someone with no support they are given our number when they move into independent accommodation and we'll go round and find out what they need – addiction services, counselling, a GP address or help with finding work. If we don't hear from them for a couple of weeks we'll give them a call to check they are OK."

Hilliard offered her services after overcoming years of drug and alcohol addiction. "It's shown me what I used to be like," she says. "Some of these people are totally isolated, and it is a constant motivator to keep myself clean because without help from places like St Mungo's I'd be where they are now."

Some of St Mungo's residents don't have family or friends to visit them, so the charity collect gifts for them from members of the public. Readers who would like to donate gifts should contact lucy.crisp@mungos.org

Other ways people can help are by becoming an e-campaigner, emailing MPs or the housing minister, or writing to local councillors – it's all about building an online community of people who will help St Mungos to raise awareness about the problems that homeless people face.

Finally, if you have yet to do your Christmas gift shopping and you think the recipients are altruistic, you might like to consider St Mungos' range of "virtual" presents, such as the £10 gift of supporting a homeless person's dog in a hostel.